A report due out after Labor Day shows an interesting trend at the federal court in San Jose where Apple Inc. won a billion-dollar mobile patent lawsuit against Samsung Electronics Inc. Both tech giants were plantiffs and defendants in the case. But there’s been a big drop here in the number of patent cases in which the plaintiffs win. The San Jose federal court is part of the Northern District Court of California.

The annual patent litigation report from PricewaterhouseCoopers shows that between 1995 and 2000, plaintiffs in Northern California had a 36 percent success rate in patent cases.

But between 1995 and 2011, the percentage of patent cases in which the plaintiffs won dropped by more than a third to just 22.6 percent. The Northern California district is one of the least likely in the country for a plaintiff to win a patent case, PwC’s research shows.

“That really stands out,” said Chris Barry, a partner in PwC’s Forensic Services practice who is a co-author of the annual study. “All of the other measures, such as how long it takes for patent trials to be resolved and the size of awards in successful complaints, have been pretty consistent.”

The downturn comes as the number of cases filed in San Jose is also rising, jumping from 31 in 2009 to 64 last year. By the middle of August, the number filed in the San Jose courthouse was 40.

Charlene Morrow, chair of the intellectual property practice at Mountain View-based Fenwick and West, said the trend is unsurprising. “This district has historically had lower success rates for plaintiffs in patent cases.”

There have also been federal court decisions that make it more difficult to file a complaint far away from where a company is headquartered. In recent years, patent plaintiffs sought to have their cases heard in the Texas Eastern District Court,which is considered more friendly to such actions. All they had to do was show that they did business in the district.

Now technology cases are more likely to be heard nearer to Silicon Valley.

“The disputes between local companies are coming back home,” Morrow said.